Nail-lift assembly for women&#39;s shoe heels



May 22, 1962 M. w. ROSS NAIL-LIFT ASSEMBLY FOR WOMENS SHOE HEELS FiledJune '7, 1960 INVENTOR. MAQS'HALL W 2055 WM E W A TTORNEYS.

United States Patent 3,035,358 NAIL-LIFT ASSEMBLY FOR WOMENS SHOE HEELSMarshall W. Ross, Mattapoisett, Mass, assignor to Acushnet ProcessCompany, a corporation of Massachusetts Filed June 7, 1960, Ser. No.34,497 2 Claims. (CI. 36-34) This invention relates to a nail forattaching lifts to the heels of women's shoes.

Very thin and long so called spike heels molded from plastic materialshave become quite popular for womens shoes. Resilient lifts areheldcompressed against the bottom of the heels by molding the liftaround the head of a hardened steel nail which is press fitted into ahole drilled up through the bottom of the heel. Since there is littleadhesion on the part of the lift material it is only the ordinary nailhead that is relied on for holding the lift in place against the bottomof the heel.

Since spike heels taper down to a very thin or narrow bottom theyreadily become wedged in gratings, cracks and other small openings infloors and pavements. When this happens the wearer usually pulls hershoe upwardly with a twisting and side, to side rocking motion to freethe heel. As a result the resilient lift becomes stretched and so badlydistorted that it is pulled off the conventional nail head used to holdit in place. Naturally, the lift must be replaced before the shoe can besatisfactorily used for walking and this in turn involves pulling theoriginal nail out of the heel, molding a new lift about its head orperhaps using a brand new lift-nail assembly, and press fitting the newnail into the heel necessarily in a Way that insures a friction tightfit which will hold the lift compressed against the bottom of the heel.These are costly time consuming procedures and removal and replacementof the nail tends to Weaken the molded plastic heel. Also, while theconventional nail head is left exposed it constitutes a hazard liable tocause injury in the hands of children or careless adults.

In the nail of this invention the bottom surface of the nail head isprovided with an annular groove which materially increases theeffectiveness of the head in retaining a resilient lift. When filledwith resilient lift material the groove and particularly its outer sidewall act as barriers against outward lateral movement of the lift and asa result the lift is securely held on the head of the nail even when itis badly distorted under deflectional or torsion-a1 strain. Although thenail is designed primarily to overcome the tendency of resilient liftsmolded from polyurethane rubber to be pulled off conventional nail headsit may of course be used with great advantage to securely hold liftsmolded from more rigid materials such as nylon or other resins since themechanical feature of the annular groove substantially increases lockingaction between the nail head and lifts of any type of material.

It is recommended that the annular groove be made as deep and as wide asthe body of the nail head will permit since the effectiveness of themechanical interlock is generallyincreased as the amount of liftmaterial contained in the groove is made greater. However, it is alsopreferred that the width of the groove be slightly less than the radialdistance out from the stern in order to provide a short substantiallyflat upper rim between the outer side wall of the nail head and the sideWall of the annular groove. This reduces the chances of chipping alongthe relatively narrow upper rim and also helps to prevent the rim fromcutting into the lift material when the lift is stretched or distorted.

The outer surface of the nail head and of the stern are preferablyknurled in the form of longitudinal striations to prevent relativerotation between the lift and the nail head and between the heel and thestem of the nail respectively. Other kinds of knurling such asintersecting diagonal lines forming a diamond shaped grid may be usedfor this purpose. The top surface of the nail head may also be providedwith a slot for preventing rotational movement.

Further details of the invention will be readily understood by referenceto the accompanying drawings in which:

FIG. 1 is a perspective view of the new form of nail.

FIG. 2 is a sectional view on an enlarged scale of a spike heel showinghow the nail prevents a resilient lift from being pulled off the nailhead when the lift is stretched and distorted.

As best shown in FIG. 1 the nail comprises a cylindrical stem 10 and adisc shaped head 12 of relatively larger cross sectional area. Anannular groove 14 extends into the body of the head from the bottomsurface thereof and forms an outer side wall 16 spaced away from thestem. The top of the side wall is in the form of a substantially flatrim 18 having a short radial width. A plurality of striations 20 are cutinto the outer wall of the head and there is a recessed slot 22 in thetop surface 24 of the head (FIG. 2). A shoulder 26 is preferablyprovided on the stem which slightly enlarges the cross sectional area ofthe base of the stem down to the nail head 12. A plurality of striations28 are cut into part of the outer surface of the stem 10 and the tip ofthe stem terminates generally in the form of a cone 30.

Prior to fitting the nail into a spike heel a lift 32 is molded aboutits head. The lift in this case is polyurethane rubber. It is importantof course that the entire head of the nail be enveloped by the lift.When the nail is placed in a mold cavity and the cavity is filled byusual techniques the shoulder 26 aligns the nail head in the cavity.

The assembled nail and lift are attached to the spike heel by insertingthe nail into a hole drilled up through the bottom of the heel. Thediameter of the hole is selected to give a friction tight fit around thesurface of the stem 10 and the striations 28 prevent the stem fromrotating in the heel. Also, the striations 20 and the slot 22 preventrelative rotation between the lift and the head of the nail. Sufficientpressure is maintained on either the lift or the heel to force the liftflush up against the bottom of the heel under compression. The exact wayin which the nail is attached to the heel may be carried out by any ofthe conventional techniques known in the art. After the lift is attachedto the heel it may be trimmed with a cutting tool to conform its outerside wall to the shape of the wall of the bottom portion of the heel.

In FIG. 2 the lower portion of a spike heel 34 is shown tilted away fromnormal vertical position and supporting the weight of the wearer. Underthese conditions one side of a resilient lift such as one molded frompolyurethane becomes compressed in toward the stem 10 but the oppositeside of the lift tends to pull away laterally from the stern and a space36 may develop between the lift and portions of the stem and the bottomof the heel. It will be seen that the annular groove 14 and its outerside wall 16 in the head 12 directly oppose this lateral movement andprevent the lift from pulling over the edge of the head. Also, thesubstantially flat rim 18 now comes into a play to reduce the chances ofthe lift being cut as its lateral movement is opposed.

Although FIG. 2' illustrates a heel distorted under one type of stressit has definitely been found to be a fact that the nail of thisinvention is effective for preventing a resilient lift from being pulledoff the nail head under J) any kind of stress and distortion to which aspike heel may be subjected either when wedged in an opening or duringwalking.

It will be understood that it is intended to cover all changes andmodifications of the preferred embodiment of the invention herein chosenfor the purpose of illustration which do not depart from the spirit andscope of the invention.

I claim:

1. A shoe heel assembly which includes a nail comprising a stem with ahead at one end thereof, said head being larger in cross section areathan the stern and having a bottom surface from which the stem projectsand a top surface opposite to and spaced away from the bottom surface,an annular groove extending into the body of the head from the bottomsurface thereof, the opening of said groove being located entirely onthe bottom surface of the head, said groove being adjacent to the stem,a lift positioned on the head which completely envelops the sides of thehead and the top surface thereof, the peripheral edge of the lift beingextended over the bottom surface of the head with the peripheral edge ofthe lift seated in said groove whereby to retain the lift in place onthe head against applied lateral forces which tend to pull theperipheral edge of the lift away from the stem.

2. A structure in accordance with claim 1 which includes shoulder on thestem which extends down to the head of the nail.

References Cited in the file of this patent UNITED STATES PATENTS2,544,878 Dratler Mar. 13, 1951 2,851,797 Ronci Sept. 16, 1958 2,852,864Quirk Sept. 23, 1958 2,852,866 Quirk Sept. 23, 1958 2,923,071 WhittedFeb. 2, 1960 2,923,072 Goldstein Feb. 2, 1960 2,935,799 Ronei May 10,1960 2,935,800 Ronei May 10, 1960 2,937,461 Trela May 24, 1960 FOREIGNPATENTS 1,183,854 France Feb. 2, 1959 1,227,916 France Mar. 7, 1960826.006 Great Britain Dec. 23, 1959

